A mid-ankle carbon fiber composite compliant energy storage prosthetic foot core

Abstract

The application discloses a kind of middle ankle carbon fiber composite material compliant energy storage artificial foot core, comprising: front carbon fiber foot plate, middle carbon fiber foot plate and rear carbon fiber foot plate;The front carbon fiber foot plate is connected with middle carbon fiber foot plate by glue-bolt;The middle carbon fiber foot plate is connected with rear carbon fiber foot plate by glue-bolt;The front carbon fiber foot plate is used to provide support force;The middle carbon fiber foot plate is used to connect front carbon fiber foot plate and rear carbon fiber foot plate and is used to store energy;The rear carbon fiber foot plate is used to provide support force and shock absorption.The middle ankle carbon fiber composite material compliant energy storage artificial foot core of the application can be more highly bionic design and more efficient energy storage;The rear carbon fiber foot plate adopts bionics design, which can not only increase the comfort during walking, but also enhance the bending energy storage effect;The energy stored by the elastic deformation of the middle carbon fiber foot plate is more applied to the forward direction, reducing unnecessary vibration;The front carbon fiber foot plate has split-toe structure.

Description

Technical Field

[0001] This invention belongs to the field of prosthetic technology, and specifically relates to a flexible energy-storing prosthetic foot core made of carbon fiber composite material for mid-ankle. Background Technology

[0002] Intelligent rehabilitation aids for prosthetic footplates are an effective means to help people with lower limb disabilities reintegrate into society and improve their quality of life. Currently, carbon fiber reinforced polymer (CFRP) energy storage prosthetic footplates have become a research hotspot in international intelligent rehabilitation aids for the lower limbs due to their advantages such as light weight, high strength, good fatigue resistance, and designability.

[0003] Currently, commercially available carbon fiber composite prosthetic footplates achieve energy storage and directional release during gait by biomimetic design of the lower limb bones, joints, and arch curves. However, the utilization rate of ground pressure during walking remains low, making prolonged, moderate-to-high-intensity walking still quite strenuous for users. Furthermore, carbon fiber composite prosthetic footplates often use perforated mechanical connections, which can easily lead to localized stress concentrations at the connection points, affecting the product's lifespan. Summary of the Invention

[0004] To address the above problems, this invention discloses a flexible energy-storing prosthetic foot core made of mid-ankle carbon fiber composite material, comprising: a front carbon fiber foot plate, a middle carbon fiber foot plate, and a rear carbon fiber foot plate; The front carbon fiber foot plate and the middle carbon fiber foot plate are connected by adhesive and bolts; The middle carbon fiber foot plate and the rear carbon fiber foot plate are connected by adhesive and bolts; The front carbon fiber footplate is used to provide support. The middle carbon fiber footplate is used to connect the front carbon fiber footplate and the rear carbon fiber footplate and to store energy. The rear carbon fiber footplate is used to provide support and shock absorption.

[0005] Furthermore, the front carbon fiber footplate is located on one side of the middle carbon fiber footplate.

[0006] Furthermore, the rear carbon fiber footplate is located on the other side of the middle carbon fiber footplate.

[0007] Furthermore, both the front and rear carbon fiber foot plates are toe-shaped structures and are provided with longitudinal through grooves.

[0008] Furthermore, the longitudinal section of the carbon fiber foot plate is an annular shape with a notch.

[0009] Furthermore, the longitudinal section of the rear carbon fiber foot plate is hook-shaped.

[0010] Furthermore, it also includes: connectors; The connector is connected to the rear carbon fiber foot plate by adhesive-bolts; The connector is used to connect the lower leg tube.

[0011] Furthermore, it also includes: rubber pads; The rubber pad is disposed on the side wall at the notch of the carbon fiber foot plate; The rubber pad is used to dampen impact vibrations.

[0012] Furthermore, it also includes: reinforcement patches; The reinforcing plates are disposed around the through holes of the rear carbon fiber foot plate; The reinforcing sheet is used to reduce the stress around the through hole, thereby improving the load-bearing capacity and service life.

[0013] Furthermore, the reinforcing sheet comprises annular carbon fibers and radial carbon fibers.

[0014] Compared with the prior art, the beneficial effects of the present invention are: 1) A higher degree of biomimetic design and more efficient energy storage; 2) The carbon fiber heel plate adopts a biomimetic design, developing a streamlined overall structure similar to the human ankle and heel, which can not only increase the comfort of walking and enhance the bending energy storage effect, but also effectively improve the overall strength and reduce joint and limb damage. 3) The middle carbon fiber footplate with a notch is connected to the front and rear carbon fiber footplates by glue and bolts, which plays a role similar to the attachment bone. At the same time, under the action of human body weight, the notch of the middle carbon fiber footplate will undergo two compression-directional rebound cycles in one gait cycle. Therefore, more of the energy stored by the elastic deformation of the prosthetic foot core can be applied to the forward direction, reducing unnecessary vibration and greatly reducing the user's walking burden. 4) The forefoot carbon fiber plate has a toe-split structure, which meets the requirements of ergonomic design. When the forefoot lands, after a certain deformation, the forefoot carbon fiber plate will be compressed and self-contacted into an inverted "6" shape, thereby rapidly increasing rigidity and providing sufficient support after cushioning and energy storage. 5) The overall design departs from the traditional frontal, arch, and sagittal plane division of carbon fiber prosthetic foot plates, and instead features a highly biomimetic series structure that provides wearers with a user experience closer to that of a normal foot.

[0015] Other features and advantages of the invention will be set forth in the description which follows, and will be apparent in part from the description, or may be learned by practicing the invention. The objects and other advantages of the invention may be realized and obtained by means of the structures pointed out in the description, claims and drawings. Attached Figure Description

[0016] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0017] Figure 1 A schematic diagram of the structure of the prosthetic foot core according to an embodiment of the present invention is shown; Figure 2 A front view of the prosthetic foot core according to an embodiment of the present invention is shown; Figure 3 A top view of the prosthetic foot core according to an embodiment of the present invention is shown; Figure 4 A schematic diagram of the structure of the reinforcing sheet according to an embodiment of the present invention is shown; Figure 5 A schematic diagram of the principal stress trajectory near the through hole according to an embodiment of the present invention is shown; Figure 6 A schematic diagram of the carbon fiber placement path in a reinforcing sheet according to an embodiment of the present invention is shown.

[0018] Reference numerals: 1. Connector; 2. Rear carbon fiber footplate; 3. Middle carbon fiber footplate; 4. Front carbon fiber footplate; 5. Rubber pad; 6. Reinforcing plate. Detailed Implementation

[0019] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0020] like Figure 1 As shown, the present invention proposes a flexible energy-storing prosthetic foot core made of mid-ankle carbon fiber composite material, comprising: a front carbon fiber foot plate 4, a middle carbon fiber foot plate 3, and a rear carbon fiber foot plate 2. The front carbon fiber foot plate 4 and the middle carbon fiber foot plate 3 are connected by adhesive and bolts; The middle carbon fiber foot plate 3 and the rear carbon fiber foot plate 2 are connected by adhesive and bolts; The front carbon fiber footplate 4 is used to provide support, providing sufficient support after cushioning and energy storage; The middle carbon fiber foot plate 3 is used to connect the front carbon fiber foot plate 4 and the rear carbon fiber foot plate 2 and to store energy, thus producing multiple energy storage effects. The rear carbon fiber footplate 2 is used to provide support and shock absorption, increase walking comfort, and enhance bending energy storage effect.

[0021] like Figure 2 As shown, the front carbon fiber foot plate 4 is located to the left of the middle carbon fiber foot plate 3, and the rear carbon fiber foot plate 2 is located to the right of the middle carbon fiber foot plate 3. There is a first gap between the rear carbon fiber foot plate 2 and the middle carbon fiber foot plate 3 above and below the connecting bolt; there is a second gap between the middle carbon fiber foot plate 3 and the front carbon fiber foot plate 4 above and below the connecting bolt.

[0022] The mid-ankle carbon fiber composite flexible energy-storing prosthetic foot core also includes: connector 1; Connector 1 is semi-cylindrical with multiple through holes on its sidewalls that abut against the rear carbon fiber foot plate 2. Connector 1 and the rear carbon fiber foot plate 2 are connected by adhesive-bolts. The top of connector 1 is connected to the calf tube by a set screw. Connector 1 is used to transmit force. Connector 1 has a hollow structure, which can reduce the weight of the flexible energy storage prosthetic foot core made of carbon fiber composite material in the mid-ankle.

[0023] Connector 1 is made of metal, preferably stainless steel. The front carbon fiber foot plate 4, the middle carbon fiber foot plate 3, and the rear carbon fiber foot plate 2 are all made of carbon fiber.

[0024] The specific steps for glue-bolt connection are as follows: First, the contact surfaces of the rear carbon fiber foot plate 2 and the middle carbon fiber foot plate 3 are treated to remove surface contaminants and improve surface bonding performance. Then, epoxy resin adhesive is evenly applied to the contact surfaces of the middle carbon fiber foot plate 3 and the rear carbon fiber foot plate 2, and finally, bolt connections are made. Similarly, the same surface treatment and connection are performed on the adhesive-bolt connection between the connector 1 and the rear carbon fiber foot plate 2, as well as on one end of the front carbon fiber foot plate 4 and the adhesive-bolt connection between the middle carbon fiber foot plate 3.

[0025] After the glue-bolt connection is assembled, it needs to be left at room temperature for 24 hours to cure (different glues have different curing times; the epoxy resin glue currently used cures in 24 hours at room temperature, but the bonding effect is better after 4 days). The glue-bolt connection method combines the fatigue resistance of adhesive bonding with the peel resistance of bolted connections, compensating for each other's shortcomings, and can give the structure superior mechanical properties and fatigue resistance.

[0026] The forefoot carbon fiber plate 4 is an inverted "6" shape, a one-piece molded structure with gaps approximately 15mm apart. It features a split-toe structure with longitudinal grooves extending 50-80mm. The stiffness of each split-toe area (first area) is less than that of other areas (second area). This split-toe structure allows for some lateral deformation, mitigating vibrations when the prosthetic foot strikes, and conforms to ergonomic design requirements. When the forefoot strikes, after some deformation, the forefoot carbon fiber plate 4 is compressed, forming an inverted "6" shape upon contact (i.e., the gaps are compressed and gradually closed into a complete inverted "6" shape), thus rapidly increasing stiffness and providing ample support after cushioning and energy storage.

[0027] The longitudinal section of the carbon fiber footplate 3 is a ring with a notch, and there are through holes at both the front and rear ends. It is connected to the front carbon fiber footplate 4 and the rear carbon fiber footplate 2 by glue and bolts, which plays a similar role to the bone attachment. At the same time, under the action of human body weight, the notch of the carbon fiber footplate 3 will undergo two compression-directional rebound cycles in one gait cycle. Therefore, more of the energy stored by the elastic deformation of the prosthetic foot core can be applied to the forward direction, reducing unnecessary vibration and greatly reducing the walking burden of the user.

[0028] like Figure 2 As shown, the longitudinal section of the rear carbon fiber footplate 2 is hook-shaped, with through holes at the upper and middle ends. The middle end of the rear carbon fiber footplate 2 is connected to the middle carbon fiber footplate 3 by adhesive-bolt. The angle of the upper end is determined according to the connection position of the connector 1 and the calf tube it is connected to, thereby increasing comfort and reducing joint and limb injuries. The angle of the middle end needs to match the middle carbon fiber footplate 3. That is, the rear carbon fiber footplate 2 and the middle carbon fiber footplate 3 will gradually come into contact during walking, resulting in a gradual increase in stiffness. This produces the variable stiffness characteristics of the overall structure in the gait cycle, meeting the different stiffness requirements of each stage in a gait cycle. The lower end has a toe-split design for shock absorption and increased stability when in contact with the ground.

[0029] The rear carbon fiber footplate has an inverted hook-shaped longitudinal section, which not only increases walking comfort and enhances flexural energy storage, but also effectively improves overall strength. Figure 3 As shown, the lower end of the rear carbon fiber footplate 2 has a split-toe structure with longitudinal through grooves extending 50cm-80mm. The stiffness of each toe tip (third area) is less than that of other areas (fourth area). Due to the split-toe design and the lower stiffness of the toe tips, the rear carbon fiber footplate 2 can bend under the action of ground reaction force while also allowing for partial lateral deformation, thus improving the overall balance of the prosthetic foot core under different road conditions and grounding methods.

[0030] like Figure 2As shown, the rear carbon fiber foot plate 2, the middle carbon fiber foot plate 3, and the front carbon fiber foot plate 4 are all provided with multiple through holes. Preferably, the rear carbon fiber foot plate 2 has 2 through holes at the upper end and 2 through holes at the middle end; the middle carbon fiber foot plate 3 has 2 through holes at the front and rear of the middle area; and the front carbon fiber foot plate 4 has 2 through holes on the right side.

[0031] In other design configurations, one end of the rear carbon fiber footplate 2 is connected to the middle carbon fiber footplate 3 via adhesive-bolt, while the other end is directly connected to the calf tube.

[0032] like Figure 2 As shown, the mid-ankle carbon fiber composite flexible energy-storing prosthetic foot core also includes: a rubber pad 5; Rubber pad 5 is set on the side wall at the notch of the middle carbon fiber foot plate 3 and is bonded with glue. Rubber pad 5 is used to dampen the impact vibration during the compression of the carbon fiber footplate 3. In one gait cycle, the notch of the carbon fiber footplate 3 undergoes two compression-directional rebound cycles, so rubber pad 5 is provided to prevent excessive friction.

[0033] like Figure 4 As shown, the mid-ankle carbon fiber composite flexible energy-storing prosthetic foot core also includes: a reinforcing sheet 6; The reinforcing plate 6 is installed around the through hole of the rear carbon fiber foot plate 2; The reinforcing plate 6 is used to reduce the stress around the through hole of the rear carbon fiber foot plate 2, thereby improving the load-bearing capacity and service life of the component. Preferably, the reinforcing plate 6 is approximately annular with a radius of 15-20mm. The reinforcing plate 6 is integrally cured with the rear carbon fiber foot plate 2 before the hole is made to ensure strength.

[0034] like Figure 5 As shown, through the overall simulation stress analysis of the rear carbon fiber foot plate 2, the principal stress distribution around the through hole on the rear carbon fiber foot plate 2 is obtained. The black dashed line is the through hole, and the black solid line is the principal stress trajectory near the through hole.

[0035] like Figure 6 As shown, the carbon fiber of the reinforcing sheet 6 is divided into two layers. The first layer of carbon fiber (black solid line) is approximately annular and is laid along the circumferential stress trajectory around the through hole on the rear carbon fiber foot plate 2. It mainly bears the circumferential stress. The second layer of carbon fiber (black dashed line) is radial and is laid along the radial stress trajectory around the through hole on the rear carbon fiber foot plate 2. It is radial in shape and mainly bears the radial stress.

[0036] The reinforcing sheet 6 was designed using fiber variable angle traction stitching technology and simulation technology, which helps to alleviate the stress concentration problem at the opening of the posterior carbon fiber foot plate 2, improve the service life of the posterior carbon fiber foot plate 2, and increase the strength at the opening. It can effectively reduce the design thickness at the opening, thereby reducing the amount of carbon fiber used and reducing the overall weight of the prosthetic foot core, which helps to reduce the burden on amputees' normal walking.

[0037] When the user is standing statically, the prosthetic foot core of this invention undergoes three energy-storing deformation stages: a buffer stage, an energy-storing stage, and a support stage. In the buffer stage, the toe tips of the rear carbon fiber footplate 2 and the front carbon fiber footplate 4 contact the ground. The toe-split structure allows for a certain degree of inversion or eversion, while simultaneously reducing overall stiffness. During this stage, the overall stiffness of the prosthetic foot core is at its lowest, allowing it to adapt to uneven ground, absorb some of the impact and excess vibration upon landing, and store energy, making the user's landing more stable and comfortable. In the energy-storing stage, due to the weight of the user, the prosthetic foot core continues to bend. The load is transferred to the middle carbon fiber footplate 3 by bolts, gradually compressing the notch structure into a closed O-shape. During this process, the initial stiffness is low, gradually increasing thereafter, allowing bending deformation while achieving an energy-storing effect that surpasses traditional carbon fiber prosthetic feet. In the support section, the middle carbon fiber foot plate 3, which has already been compressed, basically does not continue to deform. The front carbon fiber foot plate 4 and the rear carbon fiber foot plate 2 continue to bend, so that the contact area with the middle carbon fiber foot plate 3 gradually increases. During this process, the stiffness increases rapidly, and the allowable deformation is very small, providing strong support for the user to stand stably.

[0038] During dynamic walking, the prosthetic foot of this invention cyclically undergoes two phases: a compression and energy storage phase and an energy release and propulsion phase. In the compression and energy storage phase, the user's center of gravity is at the rear of the prosthetic foot, with the heel of the rear carbon fiber footplate 2 contacting the ground first, followed by the forefoot. This rapidly occurs similarly to the three phases of cushioning, energy storage, and support that occur in a static process, with each carbon fiber footplate storing most of the energy upon landing. In the energy release and propulsion phase, the user's center of gravity shifts forward and upward to the forefoot, with the weight primarily borne by the middle carbon fiber footplate 3 and the forefoot carbon fiber footplate 4. The energy stored in the heel, including the energy stored by the bending deformation of the rear carbon fiber footplate 2 and the energy stored by the compression of the middle carbon fiber footplate 3 into an O-shape, is released sequentially along the ankle joint's forward direction, increasing the upward and forward reaction force when the user pushes off the ground, making walking more efficient and effortless.

[0039] The flexible energy-storing prosthetic foot core made of carbon fiber composite material proposed in this invention has an overall design that departs from the traditional frontal, arch, and sagittal plane division design of carbon fiber prosthetic foot plates. Instead, it features a highly biomimetic series structure that can provide wearers with a user experience that is closer to that of a normal foot.

[0040] Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A flexible energy-storing prosthetic foot core made of mid-ankle carbon fiber composite material, characterized in that, include: Front carbon fiber footplate (4), middle carbon fiber footplate (3) and rear carbon fiber footplate (2); The front carbon fiber foot plate (4) and the middle carbon fiber foot plate (3) are connected by adhesive-bolts; The middle carbon fiber foot plate (3) and the rear carbon fiber foot plate (2) are connected by adhesive-bolts; The front carbon fiber footplate (4) is used to provide support. The middle carbon fiber footplate (3) is used to connect the front carbon fiber footplate (4) and the rear carbon fiber footplate (2) and to store energy; The rear carbon fiber footplate (2) is used to provide support and shock absorption; Both the front carbon fiber footplate (4) and the rear carbon fiber footplate (2) are toe-shaped structures and are provided with longitudinal through grooves. The longitudinal section of the carbon fiber foot plate (3) is an annular shape with a notch; The longitudinal section of the rear carbon fiber foot plate (2) is hook-shaped.

2. The flexible energy-storing prosthetic foot core made of carbon fiber composite material for mid-ankle as described in claim 1, characterized in that, The front carbon fiber footplate (4) is located on one side of the middle carbon fiber footplate (3).

3. The mid-ankle carbon fiber composite flexible energy-storing prosthetic foot core according to claim 2, characterized in that, The rear carbon fiber footplate (2) is located on the other side of the middle carbon fiber footplate (3).

4. The flexible energy-storing prosthetic foot core made of carbon fiber composite material for mid-ankle as described in claim 1, characterized in that, Also includes: Connector (1); The connector (1) is connected to the rear carbon fiber foot plate (2) by adhesive-bolt; The connector (1) is used to connect the lower leg tube.

5. The mid-ankle carbon fiber composite flexible energy-storing prosthetic foot core according to claim 1, characterized in that, Also includes: Rubber pad (5); The rubber pad (5) is placed on the side wall at the notch of the carbon fiber foot plate (3); The rubber pad (5) is used to dampen impact vibration.

6. The flexible energy-storing prosthetic foot core made of carbon fiber composite material for mid-ankle as described in claim 1, characterized in that, Also includes: reinforcement sheet (6); The reinforcing sheet (6) is disposed around the through hole of the rear carbon fiber foot plate (2); The reinforcing sheet (6) is used to reduce the stress around the through hole, thereby improving the load-bearing capacity and service life.

7. The mid-ankle carbon fiber composite flexible energy-storing prosthetic foot core according to claim 6, characterized in that, The reinforcing sheet (6) includes annular carbon fibers and radial carbon fibers.

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